Blower control



July 30, 1940- L. M. PERSONS BLOWER CONTROL Filed July 3, 1936 AME/Ira? LA weewcs M Parsons 75 v ,6 .5) diam 55 5/ 5/; 41702145):

Patented July 30, 1940 UNITED STATES ,PATENT OFFICE BLOWER common Application July 3, 1936, Serial No. 88,715 Claims. (01. eat-1o) The present inventionrelates generally to automatic blower control mechanism, and more l5 mechanism which includes means for actuating a blower at low speed for one furnace casing temperature, and at high speed for another :furnace casing temperature.

Another object is to provide blower contro m mechanism which includes means for changing .the speed of the blower iromi low to high at a predetermined temperature of the furnace casing. I

It will be understood that the invention is of 5 broader application than solely to the control of furnace blowers. It is, therefore, an object to provides plurality of inter-related but independently adjustable controls operable in response to changes in physical conditions to pro= vide variable operation oi some suitable operated mechanism.

Other objects and advantages will appear from the following description, taken in conjunction with the accompanying drawing, in which Fig. l is a front view of two inter-related thermostats employed in a prefierred embodi merit of the present invention mounted on a coon support. I V

, Fig.'2 is a section on the line 2-42 of Fla-l.

Fig. 3 is a diagrammatic View showing the wiring hook-up between two thermostats, as disclosed in Fig. l, a transformer, and. a motor of a furnace blower, r RTeierring more particularly to the drawing by reference numerals, it indicates generally a pair of thermostats mounted as a unit and adapted to automatically control the speed, of a motor. of a furnace blower in a set-upcontemplated by the present invention. A single contact or single- 50 throw thermostat II and a double contact or double-throw thermostat i2 are mountedpas a unit, on a base I3 which, in the present instance, isshown as a flat, preierably non-conductive, plate. Thebase l3 has openings it therein, by means'ot which the unit maybe fixed upon a support. The thermostats shown and used'in the present embodiment pf my invention are like'the one which is described in detail in my copending application Serial No. 80,990, filed May 21,1936, now Patent No. 2,145,950, dated 5 Feb. 7, 1939, v p

In Fig. 2, there is shown a central section through the thermostat 42, which includes a plate It ofnon-conductive material, and a U- shaped member it between and to which the W operating parts of the thermostat are enclosed and connected. A cover it serves to surround the ii-member, and is iastened'to the plate. The thermostat assemblage is mounted on the base it: by screws it, or the like, which extend 35 through cooperating holes in the base, the cover and the ill-member. A tube 28 containing a thermally-sensitive fluid is connected to the u-mernber to by means of an externally threaded sleeve 2B which is held in place by a nut 22. 2c The tube 26 has a bulb 23 at an end remote from the thermostat and encloses, at the end adjacent the thermostat, a wire 26 having a head 25. A double; diaphragm at is fixed to the sleeve 2!! and is adapted to receive between its elements 2'17 and 28 the thermally-sensitive fluid. A stud 293 is fired to the element 28 and includes a circumferential flange 3b which is adapted to recelve, against dneface, the washer Aprimary lever 32 is pivoted to the iJ-member ii: at so and includes an opening 3 1 by means of which it is adapted to surround, for free movement, the stud 20. Between the Washer 35 and the primary lever 32 there is disposed a stiff spring A sleeve 36 is threadedonto the stud at the end I remote from the diaphragm and abuts, for adjustable relation, projections ill on the primary lever 232; An associated dial it? and an operating lrnob it are fined to the sleeve 35. The dial it has a projection 38' adapted to abut an out standing portion th of a bracket d5, described below, to prevent complete rotation of the dial.

' A secondary lever, generaliy indicated M3, is pivoted on thou-member it at 86. The secondary lever 40 includes a pivot portion 42 which has an offset 53. A tension spring 44 is ,connected'at one end to the oflset 43 and at the other end to a bracket 45 connected to the external face of the plate 15. The secondary, lever 40 further includes an, intermediate nonconductive portion 46 to which is connected, by a screw 41, or the like, a switch blade 48. The screw 41 serves as a terminal to which the switch.

lead 48 isconnected. The switch blade carries a double contact 50, and at the end remote from the screw 41 supports anarmature, generally indicated 5|, which includes. a relatively nonpermeable element 52 and relatively permeable elements 53 and 54.

The switch blade 48 is adapted to move between identical switch plates, each of which is generally indicated 55 and each of which includes a fixed portion 51 and a relatively movable portion 58 carrying a contact 59 adapte =to cooperate with the double contact 55. As closed in Fig. 2, the left switch plate 55 is supported by a switch backing plate 55 which rests on a permanent magnet 5|, between the legs of which the armature 5| is adapted tomove. The magnet 8|, the switch backing plate and the switchplate 55 are mounted, as a unit, in insulating relation to the U-member l5 by means of the screw 52, the insulation 53 and the 'brad 54. The right switch plate 55 is supported by a switch backing plate 51 which is connected to theplate I5 by a screw 58. The screw 58 serves as a terminal for one of the leads to the thermostat. Besides the screw terminal 58, the thermostat has screw terminals 69 and 15, located as shown'in Fig. 1.

Leads l5, l5 and I8 connect with the screw terminals 58, 59 and 15, respectively. The thermostat H is a duplicatelof the thermostat I2, except for the fact that it includes but one set of contacts, inasmuch as, for the present purpose, it is necessary for this switch to close in only one direction. Having. only one set of contacts, but two leads are connected ,to this thermostat, indicated at 19 and 85, which make con-, tact at the screw terminals 5| and 52, respectively.

In Fig. 3, there is shown, in diagrammatic form,

the.electrical relation between the thermostats II and I2, a transformer generally indicated-53,

coil beingconnected by the lead to the terminal 82. The circuit is completed through the switch of the thermostat.

In thesecondary circuit, the lead 18 is connected at one end to the terminal I5 and at the other to one side of the secondary coil 85. A lead 92 connects the other side of the secondary coil'85 with one motor terminal 93. The other motor terminal 94 is connected by the lead 15 to the terminal 58. The lead 15 is connected at one end to the terminal 59 and at the other in series with half of the'coil windings of the secondary coil 85 at 95. Thus, the secondary in cludes two parallel circuits which are selectively closed by the secondary lever 45 of the thermostat alternately engaging one, of the contacts 58.

Operation The control mechanism |5 may be installed in any convenient place within the furnace room..

or within a room above the basement. But the further removed from the furnace the device is placed, the longer must be the tubes 25, inasmuch as the bulbs 23 must be disposed for intimate association with the furnace casing so that the furnace heat may be transferred to the bulbs for operation of the thermostats.

In the illustration of the drawing, the thermostat H is set to close at a temperature of 125 left to the right contact (Fig. 2) at 163.

while the thermostat is set to shift from the Thus, (Fig. 3) when the heat of the furnace casing 'reaches 125, the fluid'in the bulb 23 and the tube 25 of the thermostat will have expanded to such a point. that the secondary lever 45 will close the contacts 55'.and 59' to complete the main circuit through the primary coil 85 of the transformer 83. .The energization of the primary coil 85 results in the energization of the coil 85 of the secondary in the manner to be described.

At the temperature of 125 at which the thermostat closes, the secondary lever 45 of the thermostat I2 will be in a position in which the contact 55 engages the left contact 59 (Fig. 2) and the circuit energized will be through half of the windings of the secondary 85 (Fig. 3),

which will operate the blower motor at low speed.

This position of the secondary lever 45 is shown in Fig. 3 in full lines. traced in detail above and, therefore, it is unnecessary to retrace it now.

When the temperature of the furnace casing reaches 163, then the thermally-responsive fluid in the bulb 23 and the tube 25 of the thermostat l2 will have expanded to a point to shift the secondary lever 45 to the right (Fig. 2 so that it closes the contact 55 with the right hand contact 59 Thisposition is shown in dotted lines in Fig. 3. In this position of the secondary lever 45 of the thermostat l2, the secondary circuit is through the full windings of the secondarycoil 85 of the transformer, which operates the motorof the blower at high speed. The circuit is traced above and, likewise, will not be retraced here.

It is thus apparent that the motor is automatically shifted from low to high speed after the temperature of the furnace has reached a predetermined point. It is highly'desirable to have the blower motor functioning at low speed when the heat isbuilding up in the furnace, and at high speed after it has attained a substantially maximum heat capacity so that the air transmitted to the room or other place to be heated is of substantially the same temperature. -It is evident that the temperature of air maintained for a considerable time .in intimate association with a fire of low heat content will be substantially equal to the temperature of air maintained in association with a hotter fire a relatively shorter period of time. This is what is accomplished by the blower operating at a low speed when the-furnace is building up andat a high speed after the furnace has reached substantially its maximum heat capacity, thereby pro.- viding hot air at the point of delivery of an even temperature. .Of course, prior to the time the furnace attains the heat of 125, the blower will not operate at all, since if it did, it would only force cold air up into the room.

The thermostats in the present invention are capable of individual adjustment and may be set to function at any temperatures. In fact, the same control mechanism may be employed in the summer time to blow air through the house or other place of installation.

when the mechanism is used for the purpose of a cooling system, the thermostat l2 will be set so that the indication S is on the pointer, S indicating some very low temperature or'a block point of the thermostat. The thermostat will be used to turn the mechanism on and off. Thus,

when the room temperature is and air circulation is desired, the knob of the thermostat II is turned to set the dial at some temperature until the room temperature drops below the dial setting, or until the dial is manipulated to break the circuit.

It is thus apparent that the automatic blower control mechanism disclosed is capable of a variety of uses and attains all of the advantages and objects sought. It is to be understood that the above description and the. accompanying drawing are given by way of illustration and example and not as limitation, the invention being limited only by the following claims. In said claims, the term temperature is to be considered as illustrative of other analogous physical conditions.

What is claimed is:

1. In a device of the kind described, a transformer having a primary, and a secondary having two taps, a thermostat connected in series with the primary of the transformer, and a second thermostat having its movable member connected in series with a furnace blower motor, and two terminals each being connected to one tap of the secondary coil of the transformer, whereby control of the motor is effected.

2. In a device of the kind described, a first thermostat including a single-throw switch blade, a second thermostat including a double-throw switch blade, each of said thermostats having thermally-sensitive means extending into heattransferring relation with a furnace casing, a

furnace blower motor, a transformer, the primary of the transformer being connected in series with the first thermostat, the secondary of the transformer being connected in series with the motor and the. second thermostat, the connection between the coils of the secondary and the second thermostat including parallel leads from opposite terminals cooperating with the double-throw switchtoserieswithhalfor alloftheturnsof the secondary, whereby at selected temperatures of the furnace casing the motor operates automaticallyat low or high speed.

45 3. m a device of the kind, described, a motor for operating an aircirculating blower, two independently adiustable thermostats, a transformer, means connecting one of said thermoltatswith the primary ofthetransformerto open orclosethecircuitthereto, means conne'ctingthe other thermostat with the secondary of the transformer for temperature selective partial or full energization thereof, and means connecting the motor in series with the second thermostat and the secondary.

4. In a mechanism of the kind described, two independent thermostats each operable to two positions, said thermostats being located to be responsive to the temperatures of an area subjected to heat changes, the first being operable at one temperature of said area, and the second being operable at a difierent temperature of said area, a device to be operated, a circuit through said device, means in said circuit having connections tovary the-electrical energy applied to the device, one of said thermostats connected with said connections, one connection in each of the two thermostat positions, and the other of said thermostats being connected to render the cirat one temperature of said area, and the second being operable at a different temperature of said area, a device to be operated, a circuit through said device, means in said circuit having at least two connections to vary the electrical energy applied to the device, one of said thermostats being operable to at least two positions and selectively adapted to be connected upon temperature variation with the connections on said means to put said means in circuit with the device to be operated and thereby to vary the energy by the selection of position of said thermostat, and the other thermostat being connected to cause said circuit to be operative in one podtion and to cause it to be inoperative to close it in the other, whereby the latter thermostat determines whether or not the device may operate, and the former determlnes the manner of operation.

mwamwos u. masons. 

